Apparatus and methods for occluding a hollow anatomical structure

ABSTRACT

A clamp having at least first and second elongate clamping portions adapted to be placed on opposite sides of the hollow anatomical structure. The first and second elongate clamping portions respectively include ends coupled together with respective resilient urging members configured to urge at least one of the first and second elongate clamping portions toward the other of the first and second elongate clamping portions from an open position into a clamping position to occlude the hollow anatomical structure. The clamp includes tissue ingrowth structure on the clamping portions.

This application is a continuation of application Ser. No. 11/994,725,filed Jul. 8, 2008 which is a U.S. National Phase Application of PCTSer. No. PCT/US2006/027553, filed Jul. 14, 2006 which claims the benefitof U.S. Provisional Application Ser. No. 60/699,309 filed on Jul. 14,2005, and generally relates to the subject matter disclosed and claimedin U.S. application Ser. No. 10/853,928, filed on May 26, 2004 (now U.S.Pat. No. 7,645,285). The disclosure of each of the above is hereby fullyincorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates generally to surgical methods andapparatus for occluding a hollow tissue structure, such as whenoccluding vessels, or pedunculated structures such as an appendix, gallbladder or appendages on the heart. More specifically, the presentinvention relates to a method and device for occluding the left atrialappendage of the heart in either an open surgical procedure or minimallyinvasive procedure.

BACKGROUND

Atrial fibrillation is a common cardiac rhythm disorder that affectsmore than two million people each year. Until relatively recently,atrial fibrillation was thought to be a nuisance arrhythmia with fewconsequences. However, recent medical research has uncovered somedevastating complications including cardiomyopathy, congestive heartfailure and stroke.

During atrial fibrillation the upper part of the heart beats (quivers)faster than the rest of the heart. This phenomenon is due to thegeneration of erratic or extra electrical signals which cause the toppart of the heart to quiver rapidly and irregularly (fibrillate) as manyas 300-600 times per minute. However, the entire heart does not beatthat fast. The heart is a muscular pump divided into four chambers, withtwo atria on the top of the heart and two ventricles on the bottomportion of the heart. Normally, the heartbeat starts in the right atriumwhen a special group of cells sends an electrical signal. These cellsare called the sinoatrial or SA node, sinus node or the heart's“pacemaker.” The signal spreads throughout the atria and to theatrioventricular or AV node. The AV node connects to a group of fibersin the ventricles that conduct the electrical signal. The electricalimpulse travels via these specialized fibers to all parts of theventricles. The specialized fibers are also known as the His-Purkinjesystem. The electrical signal must follow this exact route for the heartto pump properly. Normally, the heart beats at 60-80 times per minute atrest. This number represents the contractions of the lower heart orventricles. During atrial fibrillation, electrical signals from otherparts of the heart disrupt the heart's normal rhythm and cause the atriato quiver or beat too fast. However, only a small number of these atrialbeats make it through the AV node, which acts like a gate to theventricles. This is fortunate, because a rapid ventricular heartbeatwould be much more dangerous and potentially fatal. However, some atrialfibrillation does make it through the AV node making the heart beatfaster than normal. An atrial fibrillation attack is usually not lifethreatening. The most significant danger is stroke.

Blood usually moves completely through the chambers of the heart. Duringatrial fibrillation, the heart is not pumping normally or efficiently.The blood begins to pool in the atria and this stagnation of blood cancause the blood to thicken and form clots. These clots are then ejectedout of the heart and into the bloodstream where they can lodge in thebrain causing a stroke. Atrial fibrillation can make stroke five timesmore likely than in the general population. When the heart experiencesatrial fibrillation there may not be enough blood pumping to the brainor other organs. This can cause dizziness, shortness of breath or organfailure. Untreated atrial fibrillation will also weaken the heart due tophenomenon known as remodeling. The heart, like the rest of the body,adapts to changes. The fast abnormal rhythm in the atria causeselectrical changes, and this can enlarge the heart.

There are three major objectives in the treatment of atrialfibrillation: the restoration of normal sinuous rhythm, control ofventricular rate during atrial fibrillation, and the prevention of bloodclot formation. Some methods of treatment for atrial fibrillationinclude pharmacological therapy, pacemakers, and surgery.

For the prevention of blood clots, research has demonstrated that theanticoagulant warfarin (e.g., Coumadin®) is effective in reducing therisk of blood clot formation and stroke but it does not totallyeliminate the risk. An anticoagulant such as warfarin interferes withthe body's natural clotting mechanism. The dosage of warfarin is highlyindividualized and must be carefully monitored with blood tests toensure safety. While this pharmacological treatment may significantlyreduce the risk of stroke, it also increases the risk of bleeding andmay be inappropriate for many atrial fibrillation patients.

As an alternative to pharmacological therapy, there are a few surgicalprocedures that isolate the left atrial appendage from the blood'scirculatory system. The left atrial appendage is a small hollowextension (i.e., a pedunculated structure) formed off the lateral wallof the left atrium. It has been referred to as a small “windsock” likestructure or a small, flat hollow finger-like protrusion. The leftatrial appendage usually contracts with the rest of the left atriumduring normal heart function thereby continually moving blood throughoutthe hollow extension. During atrial fibrillation, the left atrialappendage often fails to contract thereby allowing the blood to poolinside the appendage, becoming stagnated. As a result, the blood becomesthicker and thrombus or clot formation may occur. These clots can beslowly ejected from the left atrial appendage into the left atrium andleft ventricle, and then released into the bloodstream thereby becomingan obstruction in the brain or other vascular structures. For thisreason, it is advantageous to prevent these clots from forming and beingdislodged into the bloodstream. One method of preventing the occurrenceof clots is to occlude the appendage thus preventing blood from enteringand forming clots. This also prevents clots already formed in theappendage from escaping into the bloodstream. Normally, the occlusion ofthe left atrial appendage is performed in conjunction with otherprocedures such as a mitral valve replacement or coronary artery bypassprocedure and not as the sole reason for the procedure.

There are several different methods being used today to occlude the leftatrial appendage. One method is percutaneous left atrial appendagetranscatheter occlusion. A small occlusion device is deployed from avenous access catheter into the left atrium and blocks the opening intothe atrial appendage. In order to access the left atrium from the venacava's right atrium, the surgeon must go through the atrial wall. Manysurgeons are uncomfortable with making an opening in this wall withoutbeing able to repair it at the end of the procedure. There are alsoissues of placing an occlusion device inside the heart. If the occlusiondevice becomes detached within the heart, the result may be fatal.

Another method of occlusion is placing a loop around the left atrialappendage and cinching it down in a manner similar to a garrote. Whentrying to place a flaccid loop around an irregular pedunculatedstructure, it can be difficult to make certain the loop is positioned atthe base of the appendage. When cinching the loop, it is very easy toover tighten the loop, and this can result in severing the delicateatrial appendage. Even a partial tear can create problems, including theinitial problem of gaining access to repair the tear. This method ofocclusion may not always seal the opening between the appendage interiorand the atrium. That is, there may still be a partial opening due to theway the appendage wall collapses during cinching of the loop. Such apartial opening could still allow some flow into and out of the atrialappendage, leading to the problems mentioned above. In addition,transforming the relatively flat structure of the appendage onto a roundhard mass, as does a cinching method, could lead to other problems.

Another method of occlusion is to place a linear surgical stapler at thebase of the appendage and a left atrial wall and staple the appendageclosed. Due to the limited access, the ability to visualize the entireatrial appendage while placing the stapler in the correct location canbe a problem. It is very difficult to make certain the staple line makesa complete occlusion of the appendage. Again, a partial occlusion of theappendage can still result in the formation and dislodgement of clots.

For the aforementioned reasons, it would be desirable to provideimproved methods and devices to reliably occlude hollow anatomicalstructures, including but not limited to the left atrial appendage ofthe heart, completely and safely. Such methods may be performed duringan open-heart surgical procedure such as a valve replacement or coronaryartery bypass. It would also be desirable to provide methods and devicesthat may be used in minimally invasive or less invasive procedures whilethe heart is beating without placing the patient on a heart-lung bypassmachine. A less invasive device may allow, for example, access througheither an intercostal space between the ribs or a supra and/orsub-xiphoid approach to gain access to the left atrial appendage. Suchdevices may allow complete visualization of the left atrial appendagefor the surgeon and permit minor placement adjustments to be made beforepermanent installation is made. The devices would also allow completeocclusion of the left atrial appendage, eliminating the risk of clotsforming in the appendage, traveling throughout the bloodstream, andpossibly lodging in the brain causing a stroke.

SUMMARY

In one aspect, the present invention is directed to a device foroccluding a hollow anatomical structure, with the device including aclamp having at least first and second elongate clamping portionsadapted to be placed on opposite sides of the hollow anatomicalstructure. The first and second elongate clamping portions respectivelyhave ends coupled together with respective resilient urging membersconfigured to urge at least one of the first and second elongateclamping portions toward the other of the first and second elongateclamping portions from an open position into a clamping position toocclude the hollow anatomical structure. The clamp comprises an annularshape configured to surround the hollow anatomical structure in the openposition and a flattened shape in the clamping position configured toocclude the hollow interior of the hollow anatomical structure.

The resilient urging members may normally spring bias at least one ofthe first and second elongate clamping portions toward the other of theelongate clamping portions. For example, any number of designs may beused for the resilient urging members, including various types ofseparate or integrally formed spring elements on the clamp. One or moregenerally U-shaped wire sections may be used at opposite ends, forexample. The clamping portions may have tissue engaging surfaces adaptedto promote tissue ingrowth, such as a tissue engaging surface havingpores with diameters sized from about 200 to about 400 microns. Thesurface may, for example, comprise a surgical grade fabric. The tissuecontacting surface may be a surface that prevents line contact with thehollow anatomical structure thereby spreading a load force exerted bythe first and second elongate clamping portions on the tissue. The firstand second elongate clamping portions may have complementary shapes incross section such that the complementary shapes fit together in theclamping position. This may be achieved through either a preformed shapein the elongate clamping portions, or by forming one or both theelongate clamping portions, or at least one or more outer layersthereof, out of a material that is deformable under load. Any otherfeatures in the above incorporated patent application may also beincorporated into the device as further disclosed herein.

In one aspect, the first and second elongate clamping portions and theresilient urging members may be formed from at least one wire member.The wire member may be formed from a material having superelasticproperties, such as a nickel-titanium alloy, or from other materialshaving suitable physical characteristics for achieving the clampingfunction. Rigid and/or resilient tubular members may be used to coverthe wire member respectively on the first and second elongate clampingportions. Such first and second tubular shaped members can, for example,provide more effective load spreading by increasing the diameter of thewire member.

In another aspect of the invention, tissue blocking members arepositioned at opposite ends of the elongate clamping portions andprevent outward egress of clamped tissue beyond the respective ends ofthe elongate clamping portions.

In another aspect of the invention, the first and second elongateclamping portions may comprise elongate generally parallel memberscapable of reorienting into a nonparallel relationship in the clampingposition. For example, the generally parallel members may reorient intoa nonparallel relationship which converges toward one end of the clampor the other end of the clamp.

Apparatus according to the invention may include a clamp with any of thefeatures discussed above, and a clamp delivery and actuation deviceincluding first and second jaws for carrying and deploying the clamponto the hollow anatomical structure.

Methods according to the invention are also contemplated and generallyinclude use of the device or apparatus as described above including anyof the desired features discussed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a first embodiment of a clamp in anopen position.

FIG. 1B shows a perspective view of the clamp in a closed position.

FIG. 1C is a cross-sectional view of the clamp of FIG. 1A in its openconfiguration, showing the wire member, rigid tubular members, and theurging members.

FIG. 1D is a cross-sectional view of the clamp of FIG. 1B in its closedconfiguration, showing the wire member, rigid tubular members, and theurging members.

FIG. 2 shows a perspective view of the occlusion clamp of FIGS. 1A-1Dand showing the ability to close in a non-parallel fashion.

FIG. 3 is a perspective view of the first stage of assembly of analternate embodiment of a clamp, showing a wire member surrounded byrigid tubular members.

FIG. 4 is a perspective view of the second stage of assembly of theclamp of FIG. 3, in which platens have been added over the rigid tubularmembers.

FIG. 5 is a perspective view of the clamp of FIGS. 3 and 4, once anouter fabric covering has been disposed over the entire surface of theclamp.

FIG. 6 is a perspective view of a deployment tool used to apply theclamp of FIG. 5, with the clamp shown in the closed position.

FIG. 6A is a cross sectional view taken generally along line 6A-6A ofFIG. 6, but illustrating an alternative embodiment of the spreader legsin an open or spread position.

FIG. 6B is a view similar to FIG. 6A, but illustrating the tool in aclosed or clamping position.

FIG. 7 is a perspective view of the deployment tool and clamp of FIG. 5with the clamp shown in the open position.

FIG. 8 shows the deployment tool and clamp of FIG. 5, with the toolholding the clamp in its closed position.

FIG. 9 shows the deployment tool and clamp of FIG. 5, with the toolholding the clamp in a partially open position immediately prior todeployment.

FIG. 10 shows the deployment tool and clamp of FIG. 5, with the tooldeploying the clamp over an appendage.

FIG. 11 shows the clamp of FIG. 5 having being deployed over anappendage.

FIG. 12 shows an alternate embodiment of a clamp in which the urgingmembers are closer to the ends of the rigid tubular members.

FIG. 13 shows an alternate embodiment of a clamp in which the clampingportions are bent to better match anatomy.

FIG. 14 shows a top view of the clamp of FIG. 13.

FIG. 15 shows an alternate embodiment of a clamp in which the urgingmembers and clamping portions are formed from a flat spring material.

FIG. 16 shows an alternate embodiment of the clamp of FIG. 12 havingmultiple-turn urging members.

FIG. 17 shows an alternate embodiment of a clamp in which the ends ofthe clamping portions overlap each other.

FIG. 18 shows an alternate embodiment of the clamp of FIG. 15 having agreater space between the clamping portions in the clamping portions'end sections.

FIG. 19 shows an alternate embodiment of a clamp in which the clampingportions and urging members are made of the same starting stock ofmaterial.

FIG. 19A is a cross-sectional view of the clamp of FIG. 19, showing theclamp in its deployed position around an anatomical structure.

FIG. 20 is an alternate embodiment of the clamp of FIGS. 19 and 19A madefrom a tube or roll of sheet metal.

FIG. 20A is a cross-sectional view of the clamp of FIG. 20 in itsclosed, pre-deployment position.

FIG. 20B is a cross-sectional view of the clamp of FIGS. 20 and 20A inits deployed position.

FIG. 21 is a side view of an alternate embodiment of a clamp, in whichthe urging members are made from elastic bands.

FIG. 22 is a perspective view of the clamp of FIG. 21, showingtissue-blocking fingers protruding from each clamping portion and withcorresponding receiving apertures.

FIG. 23 is a perspective view of the distal end of an endoscopic tooluseful for applying a clamp in accordance with the invention.

FIG. 24A is cross sectional view of FIG. 23 taken along line 24A-24A ofFIG. 23.

FIG. 24B is a cross sectional view similar to FIG. 24A, but illustratingthe tool in a closed or clamping position.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

FIGS. 1A and 10 show one embodiment of a left atrial appendage occlusionclamp 10 in an open position with spaced apart rigid clamping portions2, 4 and resilient or elastic urging members 6, 8 at opposite ends ofeach clamping portion 2, 4. Clamping portions 2, 4 may be tubular, andboth clamping portions 2, 4 may be at least substantially parallel toeach other when at rest, i.e., when they are not being used to clamptissue. Clamping portions 2, 4 may also be of substantially equal lengthor of different length, and each may be of larger outer diameter thanthe wire that may be used to form each of the urging members 6, 8. Inthis regard, the wire forming urging members 6, 8 can extend through thehollow interiors of the clamping portions 2, 4. In this illustrativeexample, the urging members 6, 8 are each shaped as a loop. The planesdefined by the looped configuration of each of the urging members 6, 8may be substantially parallel to each other and, in turn, substantiallyperpendicular to each of the clamping portions 2, 4. Of course, otherangular orientations are possible as well.

FIGS. 1B and 1D show the same clamp 10 of FIGS. 1A and 1C with theclamping portions 2, 4 in their normally biased together positions.Contact between the clamping portions 2, 4 may occur initially alongtheir entire parallel lengths as shown. Of course, when clampingportions 2, 4 are covered in fabric or other material as laterdescribed, contact may occur between the fabric or other materialinstead. In FIGS. 1A-1D, only the structure and relative positions ofthe rigid members 2, 4 and urging members 6, 8 are shown. The finalassembly is depicted in FIGS. 3, 4 and 5 which, although describing aslightly different embodiment, show the general steps in theconstruction of each embodiment. The clamping portions 2, 4 may be madefrom rigid tubes 12, 14 of a rigid metal such as titanium disposed overa wire member 16. In this embodiment, titanium is used for itscompatibility with MRI imaging, its biocompatibility and its galvaniccompatibility with the wire member 16 when the wire member 16 is formedfrom superelastic materials such as a nickel titanium alloy. Thisembodiment and the other embodiments disclosed herein may use asuperelastic material such as a nickel titanium alloy to form the urgingmembers 6, 8. Superelastic properties will allow the material to begreatly extended to open the clamping portions 6, 8 of the clamp 10without permanently deforming the material. These superelastic materialscan also be compatible with MRI imaging and easily tolerated as animplant material in the body. The rigid tubular members 12, 14 of thisembodiment are mechanically fastened to the underlying wire member 16preferably by mechanically swaging the titanium tubes 12, 14 to the wiremembers 16. Although a single, continuous wire member is shown directedthrough both clamping portions 2, 4 and urging members 6, 8, the clamp10 of this embodiment may also be made with two or more wires, or withany other suitable components.

As shown in FIG. 2, in addition to being able to close on tissue oranatomical structure in a parallel fashion, the clamp 10 can also applyforce to the anatomical structure in a nonparallel clamping fashion.This allows the clamp 10 to accommodate non-uniform tissue thicknessover the length of the clamping portions 2, 4. In addition, withseparate urging members 6, 8 at opposite ends of the clamping portions2, 4 the nonparallel clamping can originate from either side of theclamp 10. The non-parallel clamping feature of this embodiment allowsthe clamp 10 to accommodate a wide range of hollow anatomical structureswith varying wall thicknesses throughout its length and breadth. Forexample, some anatomical structures such as atrial appendages 40 (FIG.9) of the heart 50 have internal structures called trabeculae, which arenon-uniform and very often cause variable thicknesses across one or moreof their dimensions. Nonuniform clamping, therefore, can be advantageousin this application for this reason or for other reasons.

FIG. 3 shows an alternate embodiment of a clamp 60 including two urgingmembers 66, 68 shaped to resemble a letter “U” instead of the morecircular loop configuration of the embodiment of FIGS. 1A-1D. As is thecase with the first clamp 10, the U-shaped urging members 66, 68 ofclamp 60 may also lie in planes generally parallel to each other andperpendicular to the axes of the clamping portions 62, 64. A potentialuse of the embodiment of FIG. 3 may lie in the lesser force exerted byU-shape urging members 66, 68 on the clamping portions 62, 64 withrespect to the force exerted by the loop-shape urging members 6, 8 ofclamp 10 in FIGS. 1A-1D, making it more suitable for clamping ofanatomical structures not requiring a relatively high clamping force.The U-shape configuration of the urging members 66, 68 generallyrequires less space in the direction perpendicular to the axes of theclamping portions 62, 64. FIG. 3 shows a first stage of assembly of theclamp 60, where the rigid tubular members 63, 65 are joined with thesuperelastic wire member 61. In this embodiment, mechanical swaging isused to join the tubular members 63, 65 to the wire 61. However,adhesives or laser welding or other methods of attachment could beeasily used instead. Similarly, it will be appreciated that rigidtubular members 63, 65 may not necessarily need to be bonded to wiremember 61 at all. One may rely, for example, on designing the rigidtubular members 63, 65 so that their inside diameters simply closely fitover the wire 61. In addition, the rigid tubular members 63, 65 couldtake on many different cross sectional shapes. Cross-sectional shapessuch as ovals, triangles or rectangles with rounded edges could bepreferable and may eliminate the addition of the load spreading platens67, 69 shown in FIG. 4, as these alternate shapes may provide a largerarea of contact against the anatomical structure to be engaged by theclamp 50. Since different anatomical structures greatly vary fromsubject to subject, it is advantageous to have a manufacturing method inwhich the length 71 of the clamp 60 can be easily varied. By cuttingrigid members 63, 65 to various different lengths, different sizeassemblies can configured.

FIG. 4 shows the next step in the assembly of the clamp. Load spreadingplatens 67, 69 made of plastic or other biocompatible material such asurethane, may be slipped over the titanium or other suitable materialtubing that forms rigid tubular members 63, 65, to provide a resilientsurface 73 to spread the load out onto a larger surface area, therebypreventing point source loading of the tissue which might otherwiseresult in cutting of the tissue before it has had a chance to becomeinternally fused. The platens 67, 69 can be assembled and applied overthe rigid tubular members 63, 65 prior to the swaging step or platens67, 69 can alternatively be manufactured in such a way so as to have alongitudinal split which allows the material to be opened and forcedonto the rigid tubular members 63, 65.

FIG. 5 shows the clamp 60 after a fabric cover material 74 made ofmaterial such as polyester has been sewn around the clamping portions62, 64 and urging members 66, 68. It will be appreciated that thismaterial or any other similar materials may be used as a full or partialcovering in any of the disclosed embodiments. Such a material ispreferably suitable to engage the tissue of the anatomical structurebeing clamped as well as that of surrounding areas. Preferably, thematerial 74 is circular warp knit fabric tube, with a diameter ofapproximately 4 to 5 mm and made from a combination of 4/100, 2/100 and1/100 textured polyester. The material 74 may also be heat-treated tocause a velour effect. The fabric or other material 74 is furthermoresewn or otherwise applied over the urging members 66, 68. In addition,fabric pieces 77 may be attached at opposite respective ends of clampingportions 62, 64 to prevent any part of the engaged anatomical structurefrom escaping the annular occlusion area 75 (FIG. 9) between theclamping portions 62, 64. In other words, fabric pieces 77 act as tissueblocking members or dams at opposite ends of the clamp. This or anothertissue blocking feature may also be implemented into any otherembodiment. This is desirable as it minimizes the probability ofunintentionally leaving any part of the engaged anatomical structureunclamped. The material 77, like material 74, can also promote tissueingrowth.

FIGS. 6 and 7 show a deployment tool 80 for opening the clamp 60sufficiently to allow an appendage 40 or other tissue or anatomicalstructure to be placed between the clamping portions 62, 64 and thenrelease the clamp 60 from the deployment tool 80 to allow the normalclosing force of the clamp 60 to be deployed onto the appendage 40 to betreated. The deployment tool 80 of this embodiment is a scissor typearrangement with transverse support members 81 a, 81 b having spreaderlegs or jaws 82 a, 82 b, 82 c, 82 d. Each arm 84, 85 of the deploymenttool 80 has two spreader legs 82 a, 82 b, 82 c, 82 d. Support members 81a, 81 b are connected to handles 84, 85 for operation as will beapparent from reviewing FIGS. 6 and 7. The spreader legs 82 a, 82 b, 82c, 82 d have curved receiver portions 83 a, 83 b, 83 c, 83 d at eachdistal end to engage the clamp 60. The receiver portions engage theclamp in opposing directions generally parallel to a plane containingboth clamping portions 62, 64. The receiver portions 83 a, 83 b, 83 c,83 d are generally concave, allowing the clamping portions 62, 64 to bemore securely engaged in the extending spreader legs 82 a, 82 b, 82 c,82 d. Alternative embodiments may consist of other methods anddeployment tool portions suitable to securely but releasably hold theclamping portions 62, 64 of the clamp 60, thus preventing the clamp 60from being released prior to proper deployment onto the treatedappendage 40 or other anatomical structure. These may include flat orcurved spreader legs 82 a, 82 b, 82 c, 82 d, and may also include, forexample, sutures 81 a, 81 b, 81 c, 81 d (see FIGS. 8-10) or othermanners of releasably joining the clamp 60 to the tool 80.

FIGS. 6A and 6B illustrate cross sectional views of clamp 60 held onlegs 82 b′, 82 d′. Identical numerals in FIGS. 6A and 6B represent likeelements of structure as compared to the embodiment of FIG. 6 and,therefore, further description of such elements is not necessary. Likereference numerals with prime (′) marks are slightly modified elementsas between the embodiments, and as described further herein. It will beappreciated that only two of four legs are shown in FIGS. 6A and 6B,however, the remaining two legs may be identically designed. Legs 82 b′,82 d′ have recesses 87 b, 87 d for complementing the shape of theclamping portions 62, 64 held therein. This shape retains the clamp onthe legs 82′, 82 d′ without any other retaining structure or elementbeing necessitated, such as one or more severable sutures 81 a, 81 b, 81c, 81 d as shown in FIGS. 8-10. In this manner, after the legs 82 b′, 82d′ are moved from the open or spread position shown in FIG. 6A to theclosed or clamping position shown in FIG. 6B to, for example, apply theclamp 60 to the left atrial appendage 40, the legs 82 b′, 82 d′ maysimply be slipped out from between clamping portions 62, 64.

FIG. 8 shows the deployment tool 80 of FIGS. 6 and 7 with the clamp 60engaged in the spreader legs 82 a, 82 b, 82 c, 82 d but in its closedposition. The clamp 60 may be moved into the general anatomical areawhere the appendage 40 or other structure is located while the clamp 60is in a closed position. This can allow for smaller entry wounds and/oreasier maneuvering to the clamping site. The clamp 60 is releasably heldonto legs 82 a, 82 b, 82 c, 82 d with respective severable sutures 81 a,81 b, 81 c, 81 d. The ability of the deployment tool 80 to securely butreleasably hold the clamp 60 therefore allows for this type ofpre-deployment movement to be effected without concern for thepossibility of premature or unwanted separation of the clamp 60 from thetool 80.

FIG. 9 shows a deployment tool 80 partially opening the clamp 60,applying a force sufficient to overcome the bias of the urging members66, 68 of the clamp 60 to close the clamping portions 62, 64 towardseach other. The tool 80 directs the clamp in a direction generallyoriented so that the appendage 40 will be approximately in the region ofthe annular opening 75 of the clamp 60. The appendage 40 is placedthrough the opening 75 of the clamp 60 between the two urging members66, 68. At the point of the procedure shown in FIG. 9, the deploymenttool 80 securely continues to hold the clamp 60 by the clamping portions62, 64, in one of the manners described above.

FIG. 10 shows the appendage 40 of FIGS. 8 and 9 being positioned in theclamp 60. Note that the spreader legs 82 a, 82 b, 82 c, 82 d are stillholding the clamp 60 open against the force of the urging members 66,68. This allows precise positioning of the clamp 60 prior to deployment.The appendage 40 is shown beginning to cross the plane defined by theclamping portions 62, 64 of clamp 60, while the points at which thespreader legs 82 a, 82 b, 82 c, 82 d exert force against the clampingportions 62, 64 are shown to fall generally outside the boundaries ofthe appendage 40. This prevents direct contact between the spreader legs82 a, 82 b, 82 c, 82 d and the appendage 40 during deployment or duringpost-deployment retrieval of the tool 80. Although FIGS. 8-10 show thelateral position of the legs 82 a, 82 b, 82 c, 82 d to be such thatthere is no direct contact between the spreader legs 82 a, 82 b, 82 c,82 d and the appendage 40, as described above, the legs 82 a, 82 b, 82c, 82 d may instead be placed laterally closer together if desired forany particular application.

FIG. 11 shows the tissue clamp 60 having been deployed on an appendage40. The sutures 81 a, 81 b, 81 c, 81 d have been cut and spreader legs82 a, 82 b, 82 c, 82 d have been removed from the clamp 60, allowing thefull force applied by the urging members 66, 68 to be applied againstthe appendage 40 by the closing bias of the clamping portions 62, 64 ofthe clamp 60. As FIG. 11 shows, the deployed position of the clamp 60 issuch that the urging members 66, 68 extending from the plane defined bythe clamping portions 62, 64 face away from the heart 50, so as tominimize unnecessary or undesirable contact of the urging members withthe heart 50. Any other orientation or configuration of urging members66, 68 may be chosen as desired or necessary.

Alternate embodiments show ways to add length to the urging members 66,68 in order to reduce the overall stress and thus prevent elastic yieldof the material. Uses of superelastic material such as nickel titaniumalloys are preferred and shown in previous embodiments, not only for itsresistance to yielding but also for its biocompatibility. However, it isalso possible to use other materials such as a spring-type biocompatiblesteel. Without departing from the scope of this invention, alternatematerials such as plastics, elastomers and metals can be used in theconstruction of urging members 66, 68 and other portions or componentsof the various clamps disclosed herein.

FIG. 12 shows an alternate embodiment of a clamp 90 whereby the urgingmembers 91, 92 are in close proximity to the ends 97 a, 97 b, 97 c, 97 dof the rigid clamping portions 93, 94. Portions 95, 96 of the urgingmembers 91, 92 serve to block the sides of the anatomical structure(e.g., appendage 40) being treated from entering the urging member areas98, 99 and potentially resulting in portions of the appendage 40 orother structure being left unclamped. The embodiment of FIG. 12 showsurging members 91, 92 formed with wire on planes parallel to each otherand generally perpendicular or at least transverse at some angle to theclamping portions 93, 94 of the clamp 90 in a manner similar to that ofclamp 10 of FIGS. 1A-1D. The urging members 91, 92 of this alternateembodiment, however, are each shaped with a double loop. Specifically,straight segments 95, 96 of urging members 91, 92 are perpendicular tothe axes of the clamping portions 93, 94. The ends of the straightsegments 95, 96 connect to looped portions of wire 102 a, 102 b, 102 c,102 d. The additional length of wire will assist with reducing overallstress on the wire.

FIGS. 13 and 14 show an embodiment of a clamp 100 similar to clamp 90 ofFIG. 12, however, the shape has been generally adapted to more closelymatch the anatomy surrounding the appendage 40 or other anatomicalstructure being treated. In this particular embodiment, the rigidclamping portions 103, 104 are curved such that, while extendinggenerally perpendicular to planes that contain urging members 105, 106,they will generally follow the convex curvature of the outer wall of theheart 50 or other organ or tissue surrounding the anatomical structurebeing treated. Another advantage of this embodiment is the ability toclamp the anatomical structure (e.g., appendage 40) at differentcross-sectional planes, which may be desirable in cases where thethickness of the appendage 40 or similar structure is very irregular,making the clamping profile of this embodiment more desirable than thesingle cross-sectional plane clamping enabled by the clamp 10 of FIGS.1A-1D for example.

FIG. 15 is yet another embodiment of a clamp 110 in which the urgingmembers 115, 116 and the rigid members 117, 118 are made of a flatspring material 111 having a generally rectangular cross-section. Theconstruction shown in FIG. 15 is formed by four separate segments 112 a,112 b, 112 c, 112 d of this flat material 111, consisting of two urgingmembers 115, 116 and two clamping portions 117, 118. The urging members115, 116 follow a generally C-shape profile, the ends of which overlapthe ends of the clamping portions 117, 118. Side clips 119 extend fromthe urging members 115, 116 and around the flat rigid clamping portions117, 118 to fix the parts together, frictionally preventing sliding ofthe urging members 115, 116 with respect to the clamping portions 117,118. The flat clamping portions 117, 118 may be rigid or semi-rigid andcan be made of various metallic or nonmetallic materials, or both. Asuitable nonmetallic material would be a plastic such as apolycarbonate. A benefit of this type of flat construction lies in theability to avoid the addition of any load-spreading surface such as theplatens 67, 69 of FIG. 4, since the clamping portions 117, 118 alreadyhave a relatively larger area of contact with the anatomical structureto be treated. The flat shape of the urging members 115, 116 as comparedto the wire construction of the clamp 10 of FIGS. 1A-1D similarlyresults in less point-loading on the clamped tissue or organ orsurrounding tissue. The ease of assembly of the embodiment of clamp 110can be appreciated as yet another benefit, as the need for the steps oflocating and swaging of rigid tubular members 63, 65 over a wire member72 is eliminated. The ability to cut the flat clamping portions 117, 118to a desired length to accommodate for smaller anatomical structures andthe ease of clip-based assembly regardless of such desired length of theclamping portions 117, 118, is also an advantage of this embodiment.

FIG. 16 illustrates a clamp 120 in accordance with another embodiment.The construction of this embodiment is similar to that of FIG. 12, butthe wire forming urging members 121, 122 includes two additionalrectilinear segments as compared to the embodiment of FIG. 12. Thus,urging members 121, 122 each have respective first loop sections 128 a,128 b, followed by rectilinear segments 125 a, 125 b perpendicular tothe clamping portions 123, 124. Second rectilinear segments 126 a, 126 bare formed parallel to the first segments 125 a, 125 b. Thirdrectilinear segments 127 a, 127 b are located immediately adjacent toand on the same plane as the first rectilinear segments 125 a, 125 b,followed by second loop segments 129 a, 129 b. As in the construction ofthe embodiment of FIG. 12, the loop sections 128 a, 128 b, 129 a, 129 bof the urging members 121, 122 in this embodiment end at the point wherethey connect to each of the two clamping portions 123, 124. The resultof this profile for urging members 121, 122 is the formation of a springcapable of exerting a higher bias force than do the urging members 91,92 of FIG. 12. Like an axial spring, the respective ends 131 a, 131 b,132 a, 132 b of the urging members 121, 122 are connected to theclamping portions 123, 124 and thus impart a closing force on clampingportions 123, 124. The advantages of this embodiment are the same asthose described above for the embodiment of FIG. 12, but with the addedbenefits that the clamping force exerted on the treated anatomicalstructure may be of a greater magnitude and lower internal stress may begenerated in the urging members 121, 122.

FIG. 17 shows another embodiment of a clamp 130 in which the ends 133,134, 135, 136 of each of the clamping portions 131, 132 crosses over theadjacent end of the opposite clamping portion, resulting in non-parallelclamping portions 131, 132. An advantage of this embodiment is theability to prevent portions of the anatomical structure being treatedfrom entering the urging areas 139, 141 of the clamp 130.

FIG. 18 shows a clamp 140 similar to that of FIG. 15 but with greaterspace between the rigid members 148, 149 at the ends near the urgingmembers 141, 142. This configuration may be more advantageous forthicker tissue such as a bowel. This embodiment primarily differs fromthat of FIG. 15 in that the middle section 143 of the C-shape of theurging member 141, 142 profile has been enlarged.

FIGS. 19 and 19A show an alternate embodiment of a clamp 150 in whichthe clamping portions 151, 152 and urging members 153, 154 are made fromthe same basic substrate material and from the same starting stock ofsuch material, preferably one approximating a tube. The substrate couldeither be a plastic or metal. This configuration would be especiallysuited for a bio-absorbable material. This material could be coated withthe same polyester as in the velour fabric noted earlier to enhancetissue ingrowth and stability of the clamp 150 until the anatomicalstructure has atrophied. Additionally, textures or porosity on thetissue gripping surfaces 155, 156 may increase friction and adhesion tothe clamped tissue until ingrowth and stability have been achieved. Theconstruction of this embodiment 150 consists of two flat clampingportions 151, 152 joined at the ends by urging members 153, 154following a loop profile and with such urging members 153, 154 eachincluding a notch 157, 158 to facilitate deployment or application totissue with a suitable tool (not shown).

FIGS. 20, 20A and 20B show a slight variation of the embodiment of FIGS.19 and 19A, depicting a different manufacturing method. This clamp 160is made from a tube or roll formed from sheet-metal. Lower costmanufacturing methods such as roll forming and metal piercing may bemore advantageous to reduce the cost of goods versus a multiple stepassembly such as that shown in other embodiments. Of course, suchbenefits must be weighed against any perceived advantages of the morecostly designs in use. Thus, this embodiment consists of the removal ofpart of the surface of a tube or roll 162, with the material thusremoved forming the clamp opening 161. A longitudinal split of the tubeis then formed into flat members 163, 164 constituting the clampingportions of this embodiment.

FIGS. 21 and 22 show another embodiment whereby the urging members 171,172 between the two rigid clamping portions 173, 174 are bands ofelastic material. The elastic bands 171, 172 connect the two clampingportions 173, 174. In addition, tissue blocking or damming fingers175-177 extend from either rigid clamping portions 173, 174 towards thecenter 178 between the two clamping portions 173, 174, therebypreventing tissue from becoming entangled in the elastic urging members.171, 172. These fingers 175-177 furthermore engage each of the oppositeclamping portions 173, 174 by entering into apertures 181-183 adaptedfor that purpose. Biocompatible urging members 171, 172 such as siliconeelastomer could be used in this configuration. In addition, the rigidmembers 173, 174 could easily be made from an absorbable polymer. Stillfurther, the assembly could be covered in a polyester velour fabric 74(FIG. 5) to promote tissue ingrowth and stability until the anatomicalstructure has had a chance to atrophy.

FIGS. 23, 24A and 24B illustrate an alternative tool 200 to thosediscussed in FIGS. 6, 6A, and 6B. While the tools discussed in FIGS. 6,6A and 6B may be used most easily in open surgical methods, it would bedesirable to provide systems better suited for less invasive procedures,such as endoscopic procedures. The tool 200 shown in FIGS. 23, 24A and24B is one example of a tool useful in such less invasive procedures andcomprises an elongate member 202 shown broken away, but which may beformed with any suitable length for access purposes through a port inthe body of a patient (e.g., subxiphoid, intercostal space, etc.). Oneset of legs 204 a, 204 b may be rigidly fixed to the elongate member 202and/or to other suitable rigid structure 205 either associated with theelongate member 202 or extending within the elongate member 202. Anotherset of legs 204 c, 204 d is coupled to a rotatable shaft 206 extendingwithin the elongate member 202. The rotatable shaft or actuating member206 may be rotated through the use of a suitable handle or knob (notshown), for example, located at a proximal end of the tool 200 outsidethe body of the patient, when in use. The legs 204 a, 204 b, 204 c, 204d have respective recesses 208 a, 208 b, 208 c, 208 d configured toreceive the clamping portions 62, 64 generally as previously described.When the pair of legs is rotated by rotation of the shaft 206, this willspread the clamping portions 62, 64 apart as shown in FIG. 24A. Rotationof the shaft 206 in the opposite direction will allow the normallyclosed clamping portions 62, 64 to naturally come together againstopposite sides of the desired tissue (not shown). The tool 212 furtherincludes one or more clamp removal members 210 coupled to anotherrotatable shaft 212 that may also be coupled to a proximally locatedhandle or knob (not shown). When this shaft 212 is rotated after theclamp 60 has been applied as shown in FIG. 24B, the clamp 60 will beurged or pushed away from the legs 204 a, 204 b, 204 c, 204 d as shownin comparing the solid line depictions to the dash-dot line depictionsin FIG. 24B. It will be appreciated that multiple clamp removal membersmay be provided for contact along the length of the clamp 60 such that amore uniform removal force is applied along the length of the clamp 60.

While the present invention has been illustrated by a description ofvarious preferred embodiments and while these embodiments have beendescribed in some detail, it is not the intention of the Applicant torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. The various features of the invention may beused alone or in any and all combinations depending on the needs andpreferences of the user. This has been a description of the presentinvention, along with the preferred methods of practicing the presentinvention as currently known.

What is claimed is:
 1. A device for occluding a left atrial appendage ofthe heart, the device comprising: a clamp having at least first andsecond elongate clamping portions configured to be placed on opposite,outside surfaces of the left atrial appendage, said first and secondelongate clamping portions being coupled together proximate respectiveends with resilient urging members configured to urge at least one ofsaid first and second elongate clamping portions toward the other ofsaid first and second elongate clamping portions from an open positioninto a clamping position to occlude the appendage, said clamp configuredto receive the appendage in the open position and occlude the hollowinterior of the appendage in the clamping position, wherein said firstand second elongate clamping portions have tissue engaging surfaces forengaging the appendage in the clamping position, and wherein said firstand second elongate clamping portions and said resilient urging membersare surrounded along an entire length thereof by a fabric structure thatpromotes tissue ingrowth in the clamping position, said fabric structureforming a closed continuous configuration lengthwise around said clamp,wherein said first and second elongate clamping portions and saidresilient urging members are formed from at least one wire member andsaid wire member is formed from a material having superelasticproperties, and further comprising first and second rigid titanium tubessurrounding said wire member respectively on said first and secondelongate clamping portions, said first and second rigid titanium tubespositioned between said at least one wire member and said fabricstructure.